use multibody by default when using FILE/Open URDF (instead of maximal coordinate rigid body+typed constraints)

examples/OpenGLWindow/stb_image_write.h

@@ -493,7 +493,10 @@ int stbi_write_png(char const *filename, int x, int y, int comp, const void *dat
    unsigned char *png = stbi_write_png_to_mem((unsigned char *) data, stride_bytes, x, y, comp, &len);
    if (!png) return 0;
    f = fopen(filename, "wb");
-   if (!f) { free(png); return 0; }
+   if (!f) { 
+	   free(png); 
+	   return 0; 
+   }
    fwrite(png, 1, len, f);
    fclose(f);
    free(png);